Identifying minerals – use your sense(s)! Minerals in the dark

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Identifying minerals – use your sense(s)!
Minerals in the dark: identifying minerals when the lights fail
Explain to pupils that there is more than one way
in which we can examine geological materials. We
are going to try to identify several minerals, using
senses other than sight, so most people will be
blindfolded!
Use good examples of any minerals that you have
available, so long as they pose no risk to pupils,
e.g. by being toxic or by having long fibres.
Prepare trays of minerals in groups, as shown in
the diagram, and cover them up.
Seat a group of pupils around each covered tray
and ask them to study a key to mineral
identification, which you have prepared in
A tray of three minerals and a blindfold
advance. (An example is given for a particular
suite of eleven minerals, with one duplicate to
Group A
Group B
make twelve, shown in the photographs. These
minerals have been divided into groups of three to
be used by four groups of pupils). Explain any
technical terms used in the key, using pictures of
good minerals like these, so that everybody
knows what to expect.
All the pupils except one in each group are then
blindfolded. The sighted pupil (the reader)
removes the cover from the tray and the
blindfolded pupils take it in turns to pick up a
mineral. The reader reads out the key in stages
and the blindfolded pupil has to decide which
answers to follow through the key, until s/he has
Group C
Group D
identified the mineral. The other blindfolded pupils
then tackle their own minerals in the same way.
Diagram for the rotation of the minerals (numbered
When all groups have finished, cover the trays
circles) around four groups (squares). In each
and move them on to the next group. Ask the
rotation, the group of minerals rotates. In this
pupils to swap jobs, and then to have a go at
case, there are three different minerals in each
identifying the new set of minerals.
group with one repeated mineral (“R”).
………………………………………………………………………………………………………………………………
The back up
Title: Identifying minerals – use your sense(s)!
Context:
Detailed knowledge of individual minerals is
seldom specified for pupils’ learning in general
science courses. However, this activity reinforces
that minerals are substances of well-defined
composition which have reliable physical
properties. They form the “building blocks” of
rocks, and it is useful to acquire some
understanding of them.
Subtitle: Minerals in the dark: identifying minerals
when the lights fail.
Topic: Pupils use their senses other than sight to
enable them to identify a range of different
minerals.
Age range of pupils: 11 -18 years
Following up the activity:
• Compare the results of the groups, building up
a list of the minerals on the board or screen.
• Invite the groups to devise their own keys,
either based around the minerals they have
already handled, or different ones.
• Discuss the difficulties in identifying the
samples which the pupils faced when in an
unfamiliar situation.
• Ask pupils what other problems blind people
might face in their daily lives and encourage a
sympathetic approach from them, when they
meet blind people themselves.
Time needed to complete activity: 30 minutes
for the activity itself, plus discussion time
Pupil learning outcomes: Pupils can:
• appreciate that we use several senses in
identifying unknown objects, often without
realising it;
• be encouraged to use a range of tests on
minerals and not rely on snap judgements
based on sight alone;
• learn to work co-operatively when many in the
group are disadvantaged by being blindfolded;
• memorise the properties of several minerals by
carrying out tests themselves.
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• Try another similar activity, using fossils
instead of minerals.
• bigger classes will require another set of 11 +
1 minerals, which may be the same as above
or different
• a set of photographs for each cluster of 16
pupils, to explain some of the terms used;
some examples are shown in the photographs
below.
• sets of small trays and an opaque cover for
each
• a key, devised to suit whichever minerals you
have available, modelled on the example
below
• a small but strong bar magnet
Underlying principles:
• Minerals are naturally occurring inorganic
compounds, (or sometimes, single elements),
with a well defined chemical composition and a
definite atomic structure.
• Minerals display reliable physical and chemical
properties.
• Common minerals may be readily identified
with the use of the senses, or by applying
simple tests.
• Most minerals are crystalline and may exhibit
good crystal faces, and/or good cleavage
faces.
• Rocks are mixtures of minerals and may also
contain rock or fossil fragments.
NOTE. Please ensure that the minerals are nontoxic and that they do not have a fibrous habit, like
asbestos. Pupils should be warned NOT to taste
any minerals, especially when blindfolded.
Thinking skill development:
Pupils build up a cognitive pattern as they work
through their minerals. Some specimens may
bring up a cognitive conflict. Applying their skills to
other samples of unknown minerals is a bridging
skill.
Useful links: www.mineralogy4kids.org (but the
diagram of the rock cycle is extremely simplified)
http://www.mindat.org/photosearch.php
Source: Written by Peter Kennett of the
Earthlearningidea team, based on an activity
written for the www.earthlearningidea.com
website by Daniel Reis and fellow students
studying for Masters’ degrees in Biology and
Geology at the University of Oporto, Portugal.
Resource list:
• A selection of different minerals, such as the
11 good examples of different common
minerals needed for each cluster of 16 pupils,
as shown here. In this example, a further
specimen of one of the minerals is also
required to make up the 12 samples
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Key
Number
Property
1
Normal density (about the same as a sandstone rock)
Much denser than normal
Mineral
Go to 2
Go to 8
2
Soapy feel; easily turned to dust; no smell
Does not feel soapy;
Talc
Go to 3
3
Brittle and smells of sulphur
Does not smell of sulphur
Sulphur
Go to 4
4
You can split off flexible flakes with your fingernail
You cannot split off flexible flakes with your fingernail
Mica
Go to 5
5
You can scratch it easily with your fingernail
You cannot scratch it easily with your fingernail
Gypsum
Go to 6
6
Crystals are long and prismatic, with a pyramid shaped end
Crystals are of equal dimensions
Quartz
Go to 7
7
Crystals are cubic
Crystals are rhombohedral (like a squashed cube)
Fluorite
Calcite
8
Mineral is roughly three times as dense as normal
Mineral is roughly twice as dense as normal
Galena
Go to 9
9
Attracts a bar magnet, balanced across your finger
Does not attract a bar magnet, balanced across your finger
Magnetite
Go to 10
10
Surface of mineral is rounded and lumpy
Surface of mineral is “stepped”
Haematite
Barite
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Quartz, showing prismatic habit
Fluorite showing cubic habit
Calcite, (cleaved crystal) showing rhombohedral
habit
Haematite, “kidney ore”
Galena, with cubic cleavage
Barite
Mica, showing platy cleavage
Gypsum
Talc
Sulphur
Magnetite
Some examples of crystals of common minerals (All photos by Peter Kennett)
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